We very clearly work in different professional environments. :)

In no particular order: Administrating a git server is similarly trivial. A repository is a folder (easy to backup, easy to repair, easy to host), and setting up a new server usually a matter of ssh key management. Don't even need to install sqlite or anything beyond the git package. Or, because the tool has wide support, you can install a wide selection of tools that manage it for you, or use a free hosting service, or a paid one.

I'm startled that you would say you can't think of anyone who would care. My entire professional experience has been developer stories about bad jobs often include details about using old or esoteric VCS systems, usually met with "ew" or "wtf" comments. Sets the flavor of the story.
Personally, in a business environment, I would take using anything except git for the org as a red flag. It's a sign that someone in leadership at the company values doing things unrelated to the core mission "their way" above doing it the easy or "paved path" way.

The standard tool is indeed not constant. Before git existed, using CVS would have been the better choice, as well as for years afterwards until it had clearly been usurped. Most projects aren't Linux when it made the switch to git.

You joke that no one really "knows" git, but... This is literally the first time I've ever seen a fossil command. I just searched for "fossil manual" and I get analog watches. It's not even available in any of my systems package managers.
Developer familiarity is a big advantage that I think you're downplaying in comparison to "there are metadata files in .git", which I don't know has ever been relevant to me in any significant way.
(Also, I thought the different systems all work basically the same? 😛)

I'd handily agree people should be using the best tool for the job. Familiarity and ease of use are significant factors in what makes a tool better.
Ability to integrate with other tools is also a major factor. Setting up continuous integration or code review tools with git is trivial with any number of different systems.

What are any of the tools you're using doing better than git? The biggest selling point you've shared for fossil is that it's functionally similar to git, and that it has better merging. I can't find anything related to merge conflicts outside of years old forum posts, and barely anything relating to merges at all, so I'm not entirely certain what makes it "better".

If it's biggest advantage is that it's similar enough to git that you can pick it up fast, why wouldn't I just use git?